21766739 has 2 divisors, whose sum is σ = 21766740. Its totient is φ = 21766738.

The previous prime is 21766721. The next prime is 21766747. The reversal of 21766739 is 93766712.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 21766739 - 2²⁰ = 20718163 is a prime.

It is a Chen prime.

It is a junction number, because it is equal to n+sod(n) for n = 21766696 and 21766705.

It is not a weakly prime, because it can be changed into another prime (21766709) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10883369 + 10883370.

It is an arithmetic number, because the mean of its divisors is an integer number (10883370).

Almost surely, 2^21766739 is an apocalyptic number.

21766739 is a deficient number, since it is larger than the sum of its proper divisors (1).

21766739 is an equidigital number, since it uses as much as digits as its factorization.

21766739 is an evil number, because the sum of its binary digits is even.

The product of its digits is 95256, while the sum is 41.

The square root of 21766739 is about 4665.4837905623. The cubic root of 21766739 is about 279.2100994081.

The spelling of 21766739 in words is "twenty-one million, seven hundred sixty-six thousand, seven hundred thirty-nine".